From d0a7ca87ab208d72b2c6a9d44e30fe20c3c0542e Mon Sep 17 00:00:00 2001 From: Andrew Burgess Date: Wed, 12 Oct 2022 11:45:53 +0100 Subject: sim/erc32: avoid dereferencing type-punned pointer warnings When building the erc32 simulator I get a few warnings like this: /tmp/build/sim/../../src/sim/erc32/exec.c:1377:21: warning: dereferencing type-punned pointer will break strict-aliasing rules [-Wstrict-aliasing] 1377 | sregs->fs[rd] = *((float32 *) & ddata[0]); | ~^~~~~~~~~~~~~~~~~~~~~~~ The type of '& ddata[0]' will be 'uint32_t *', which is what triggers the warning. This commit makes use of memcpy when performing the type-punning, which resolves the above warnings. With this change, I now see no warnings when compiling exec.c, which means that the line in Makefile.in that disables -Werror can be removed. There should be no change in behaviour after this commit. --- sim/erc32/Makefile.in | 3 --- sim/erc32/exec.c | 7 ++++--- 2 files changed, 4 insertions(+), 6 deletions(-) (limited to 'sim/erc32') diff --git a/sim/erc32/Makefile.in b/sim/erc32/Makefile.in index 786ae1d..41830aa 100644 --- a/sim/erc32/Makefile.in +++ b/sim/erc32/Makefile.in @@ -32,9 +32,6 @@ SIM_EXTRA_CLEAN = clean-sis # behaviour of UART interrupt routines ... SIM_EXTRA_CFLAGS += -DFAST_UART -I$(srcroot) -# Some modules don't build cleanly yet. -exec.o: SIM_WERROR_CFLAGS = - ## COMMON_POST_CONFIG_FRAG # `sis' doesn't need interf.o. diff --git a/sim/erc32/exec.c b/sim/erc32/exec.c index ef93692..26d48c0 100644 --- a/sim/erc32/exec.c +++ b/sim/erc32/exec.c @@ -1345,7 +1345,7 @@ dispatch_instruction(struct pstate *sregs) if (mexc) { sregs->trap = TRAP_DEXC; } else { - sregs->fs[rd] = *((float32 *) & data); + memcpy (&sregs->fs[rd], &data, sizeof (sregs->fs[rd])); } break; case LDDF: @@ -1373,11 +1373,12 @@ dispatch_instruction(struct pstate *sregs) } else { rd &= 0x1E; sregs->flrd = rd; - sregs->fs[rd] = *((float32 *) & ddata[0]); + memcpy (&sregs->fs[rd], &ddata[0], sizeof (sregs->fs[rd])); #ifdef STAT sregs->nload++; /* Double load counts twice */ #endif - sregs->fs[rd + 1] = *((float32 *) & ddata[1]); + memcpy (&sregs->fs[rd + 1], &ddata[1], + sizeof (sregs->fs[rd + 1])); sregs->ltime = ebase.simtime + sregs->icnt + FLSTHOLD + sregs->hold + sregs->fhold; } -- cgit v1.1